After a while it starts eating and it's very destructive (7)
I believe the answer is:
termite
'it's very destructive' is the definition.
I can't judge whether this definition defines the answer.
'after a while it starts eating' is the wordplay.
'after a while' becomes 'term' (I can't explain this - if you can you should believe this answer much more).
'starts' says to take the initial letters.
The first letter of 'eating' is 'e'.
'term'+'it'+'e'='TERMITE'
'and' is the link.
Can you help me to learn more?
(Other definitions for termite that I've seen before include "Woodworm of warmer regions" , "Social type" , "Social insect" , "Mound builder" , "Whitish antlike insect" .)